JPH10163174A - Patterning method of thin film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a patterning method wherein a film to be etched which is composed of at least two different materials or film thicknesses can be etched by one patterning process. SOLUTION: A gate wiring 2 is formed on an insulating substrate 1, and a gate insulating film 3, an i layer 4 composed of undoped amorphous silicon and an n<+> layer 5 composed of silicon doped with high concentration phosphorus or the like are sequentially laminated on the gate wiring 2. When resist 6 is spread and patterned, a thin resist part 6a is formed on a desired position, and dry etching is performed while the resist 6 is subjected to ashing. The n+ layer 5 and the i layer 4 on a part position on which the resist 6 does not exist are etched, and the n<+> layer 5 under the thin resist part 6a is etched. Resist 6b after etching is thinned since a part of it is subjected to ashing. Then the resist 6 is exfoliated, and the channel part 7 of a TFT is formed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for patterning thin films such as semiconductors, conductors and insulators, and more particularly to a method for patterning various thin films constituting a liquid crystal display device.

[0002]

2. Description of the Related Art As a liquid crystal display device, a so-called active matrix substrate in which a thin film transistor (TFT) or an MIM element formed of amorphous silicon is formed on a substrate together with a plurality of gate lines and a plurality of data lines crossing each other. Is known.

On the other hand, a thin film patterning method is shown in FIG.
As shown in (a), a film to be etched 52 is formed on an insulating substrate 51, and a resist 53 is formed on the film to be etched 52.
Is applied.

A photomask in which a light-shielding portion 54 on which a light-shielding film such as chromium or chromium oxide is formed and a light-transmitting portion 55 on which no light-shielding film is formed are formed in accordance with a desired pattern. The light 5 is applied to the resist 53 through 56.
7 is exposed to light, and as shown in FIG. 5B, a photosensitive resist 53a is obtained.

Next, as shown in FIG. 5C, the exposed resist 53a is removed by developing to obtain a resist 53 having a desired pattern. Further, FIG.
As shown in FIG. 5, the film to be etched 52 is patterned by wet etching or dry etching, and the resist 53 is peeled off as shown in FIG.

It is necessary to repeat such steps by the number of films 52 to be etched and to overlap the films to be etched.

As shown in FIG. 6, an inverted staggered T without using an etching stopper on the active matrix substrate.
When forming an FT, the following manufacturing process is used.

First, as shown in FIG. 7A, a gate wiring 58 is formed on an insulating substrate 51, a gate insulating film 59 is formed on the gate wiring 58, and an i-layer 60 made of undoped amorphous silicon is formed. And an n ⁺ layer 61 made of silicon doped with phosphorus or the like at a high concentration.

Then, as shown in FIG. 7B, a resist 53 is applied and patterned, and as shown in FIG. 7C, the i-layer 60 and the n ⁺ layer 61 are etched to
As shown in (d), the resist 53 is peeled off.

Next, as shown in FIG. 7 (e), a resist 53 is applied and patterned into a pattern different from the pattern shown in FIG. 7 (b), and as shown in FIG.
As shown in FIG. 7 (g), only the n ⁺ layer 61 of the channel portion 62 of the FT is etched, and the resist 53 is peeled off to form the channel portion 62, thereby forming the data wiring 63 and the pixel electrode 64. To obtain a TFT.

In order to form an inverted staggered TFT without using an etching stopper, it is necessary to perform at least two thin film patterning steps.

[0012]

As described above, when etching films to be etched made of at least two different materials or film thicknesses, the number of patterning steps for each film to be etched must be performed. However, there is a problem that the length of the photomask becomes longer, and the photomask is displaced in each patterning process.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned conventional problems, and provides a patterning method capable of etching a film to be etched made of at least two different materials or film thicknesses in a single patterning step. It is intended to provide.

[0014]

In order to achieve the above object, a method of patterning a thin film according to the present invention comprises the steps of: applying a resist on a film to be etched;
A step of exposing the resist using a photomask having a desired pattern, a step of developing the resist into a desired pattern, and a step of dry-etching the film to be etched,
Developing the resist to at least two different thicknesses,
Dry etching the film to be etched while ashing the resist.

According to a second aspect of the present invention, there is provided a method of patterning a thin film according to the first aspect.
The resist is continuously exposed using a photomask having at least two different patterns, and the resist is developed to at least two different film thicknesses.

According to a third aspect of the present invention, there is provided a method of patterning a thin film according to the first aspect.
The resist is exposed to light using a photomask having at least two portions having different transmittances, and the resist is developed into at least two different film thicknesses.

According to a fourth aspect of the present invention, in the thin film patterning method of the second or third aspect, the resist is formed by laminating at least two resists having different sensitivities. Features.

According to the thin film patterning method of the present invention, the resist is developed into at least two different film thicknesses,
By dry-etching the film to be etched while ashing the resist, since the film to be etched under the resist is etched after the resist is ashed, the etching amount of the film to be etched is controlled by the thickness of the resist. Thus, a film to be etched made of at least two different materials or film thicknesses can be patterned by one etching.

This can be easily realized by continuously exposing the resist using a photomask having at least two different patterns and developing the resist to at least two different film thicknesses.

Further, the present invention can also be easily realized by exposing the resist to light using a photomask having at least two portions having different transmittances and developing the resist to at least two different film thicknesses. .

Further, since the resist is formed by laminating at least two resists having different sensitivities, it is easy to control the resist to at least two different film thicknesses, and the resist film thickness can be accurately adjusted. Can be controlled.

[0022]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a process diagram illustrating the concept of the present invention, FIG. 2 is a process diagram illustrating a first patterning method according to the present invention, and FIG. 3 is a process diagram illustrating a second patterning method according to the present invention. FIG. 4 is a process chart for explaining a third patterning method according to the present invention.

The present invention will be described with reference to FIG. As shown in FIG. 1A, an insulating substrate 1 made of glass or the like is used.
A gate wiring 2 made of Ta or the like is formed thereon, a gate insulating film 3 made of a silicon oxide film or the like on the gate wiring 2, and an i-layer 4 made of undoped amorphous silicon.
N ⁺ made of silicon doped with phosphorus and the like at a high concentration
The layers 5 are sequentially laminated.

Next, as shown in FIG. 1B, when the resist 6 is applied and patterned, a thin portion 6a of the resist is provided at a desired portion, and as shown in FIG. by dry etching while ashing 6, together with the resist 6 is etched n ⁺ layer 5 and the i layer 4 of the portion does not exist, to etch the underlying n ⁺ layer 5 of the thin portion 6a of the resist.
The resist 6b after the etching is thin because a part thereof is ashed. Then, as shown in FIG. 1D, the resist 6 is peeled off to form a channel portion 7 of the TFT.

As described above, by performing the dry etching while ashing the resist 6, the n ⁺ layer 5 and the i layer 4 in the portion where the resist 6 does not exist are etched as usual. Then, the thin portion 6a of the resist
Since the n ⁺ layer 5 under the n ⁺ layer 5 is etched after the thin portion 6a of the resist is completely etched before the n ⁺ layer 5 is etched, the n ⁺ layer 5 below the n ⁺ layer 5 is not etched. Can be controlled. The part of the resist 6 having a normal thickness is partially ashed and thinned, and becomes like the etched resist 6b. However, since the resist 6 is not completely eliminated, the n ⁺ layer 5 and the underlying n ⁺ The i-layer 4 can be controlled so as not to be etched.

Ashing of resist 6 and n ⁺ layers 5 and i
In order to simultaneously perform the etching of the layer 4, a mixed gas of HCl + SF ₆ + O ₂ may be used as the process gas.

The thickness of the thin portion 6a of the resist may be determined based on the ashing rate of the resist 6 in the actual process and the thickness and the etching rate of the n ⁺ layer 5 and the i layer 4.

More specifically, the n ⁺ layer 5 and the i layer 4 where the resist 6 is not present are etched, and at the same time, the thin portion 6a of the resist is ashed and the underlying n ⁺ layer 5 is etched. Since the n ⁺ layer 5 is similarly etched at the portion where the resist 6 is not present and at the thin portion 6a of the resist,
The etching time for the i-layer 4 and the ashing time for the thin portion 6a of the resist may be the same.

For example, the ashing rate of the resist 6
The ratio of the etching rate of the n ⁺ layer 5 to the etching rate of the i layer 4 is 5: 2: 1, the thickness of the n ⁺ layer 5 is 50 nm, the thickness of the i layer 4 is 100 nm, and 10% overetching is performed. Is performed, the thin portion 6a of the resist
The thickness of the resist 6 having a normal thickness may be 700 nm or more. In particular, it is necessary to accurately control the thickness of the thin portion 6a of the resist.

Here, a patterning method for forming at least two resists 6 having different thicknesses will be described with reference to FIGS.

(First Patterning Method) As shown in FIG. 2A, a film 8 to be etched is formed on the insulating substrate 1 and a resist 6 is applied on the film 8 to be etched. The light-shielding portion 9 on which a light-shielding film such as chromium or chromium oxide is formed, and the light-transmitting portion 10 on which no light-shielding film is formed,
The resist 6 is irradiated with the first light 12a through a first photomask 11a formed according to a desired pattern, and is exposed to light, as shown in FIG. I do.

Next, as shown in FIG.
The resist 6 is irradiated with a second light 12b through a second photomask 11b in which the light-transmitting portion 10 is formed in accordance with a desired pattern, and is exposed as shown in FIG. 2D. Next, a photosensitive resist 6c having a different thickness is formed.

Then, as shown in FIG. 2E, the exposed resist 6c is removed by developing, thereby obtaining a resist 6 having a desired pattern having a thin portion 6a of the resist.

Further, as shown in FIG. 2F, by performing dry etching while ashing the resist 6, the film 8 to be etched in a portion where no resist is present is etched, and the thin portion 6 of the resist is removed.
A part of the etching target film 8 under the layer a is etched.
The resist 6b after the etching is thin because a part thereof is ashed.

Then, as shown in FIG. 2 (g), the resist 6 is peeled off, and a desired pattern 8 having a thin film 8a to be etched is formed, and the patterning is completed.

As described above, in order to form the resists 6 having at least two different thicknesses, the exposure may be continuously performed using the photomasks 11 having at least two different patterns.

In the case of FIG. 2, the first light 12a controls the film thickness of the thin portion 6a of the resist, and
What is necessary is just to irradiate with the light quantity that a becomes a desired film thickness,
The second light 12b may be irradiated with a light amount such that the resist 6c at a portion to be removed by development can be completely exposed to the resist 6c.

(Second Patterning Method) As shown in FIG. 3A, a film 8 to be etched is formed on the insulating substrate 1, and a resist 6 is applied on the film 8 to be etched. The light-shielding portion 9, the light-transmitting portion 10, the first semi-transmitting portion 13a having the first transmittance, and the second semi-transmitting portion 13b having the second transmittance form a desired pattern. The light 1 is applied to the resist 6 via the photomask 11 formed accordingly.
2 to expose.

At this time, the light 12 transmitted through the first semi-transmissive portion 13a becomes the light 12c having the first transmissivity, and the light 12 transmitted through the second semi-transmissive portion 13b becomes the light 12d having the second transmissivity.
Therefore, as shown in FIG. 3B, photosensitive resists 6c having different thicknesses can be formed.

Then, as shown in FIG. 3C, the exposed resist 6c is removed by developing, thereby obtaining a resist 6 having a desired pattern having a thin portion 6a of the resist and a thinner portion 6d of the resist.

Further, as shown in FIG. 3D, by performing dry etching while ashing the resist 6, the film 8 to be etched in a portion where the resist does not exist and the film to be formed in the lower layer of the resist thin portion 6a are formed. A part of the etching film 8 and a part of the etching target film 8 under the thinner portion 6d of the resist are etched. The resist 6b after the etching is thin because a part thereof is ashed.

Then, as shown in FIG. 3E, the resist 6 is peeled off, and the film to be etched 8 having a desired pattern including the film to be etched 8a having a small thickness and the film to be etched 8b having a smaller thickness is formed. After the formation, the patterning is completed.

As described above, in order to form at least two resists 6 having different film thicknesses, the photomask 11 having at least two portions having different transmittances is formed.
May be used to perform one exposure.

In the case of FIG. 3, the first semi-transmissive portion 13a controls the film thickness of the thin portion 6a of the resist, and the first semi-transmissive portion 1a controls the thin portion 6a of the resist to have a desired film thickness.
3a may be set, and the second semi-transmitting portion 13b may be set.
The thickness of the thinner portion 6d of the resist may be controlled, and the transmittance of the second semi-transmitting portion 13b may be set so that the thinner portion 6d of the resist has a desired thickness. The light 12 may be irradiated at such an amount that the resist 6 c at the portion to be removed by development can be completely exposed to the resist 6 c.

(Third Patterning Method) As shown in FIG. 4A, a film 8 to be etched is formed on the insulating substrate 1, and a first resist 6e having a different sensitivity is formed on the film 8 to be etched. The second resist 6f and the third resist 6g are applied and laminated.

The light-shielding portion 9, the light-transmitting portion 10, and the first
A first semi-transmissive portion 13a having a transmissivity of and a second semi-transmissive portion 13b having a second transmissivity are formed via a photomask 11 formed according to a desired pattern.
The first resist 6e, the second resist 6f, and the third resist 6g are exposed to light 12 to be exposed.

At this time, the light 12 transmitted through the first semi-transmissive portion 13a becomes the light 12c having the first transmissivity, and the light 12 transmitted through the second semi-transmissive portion 13b becomes the light 12d having the second transmissivity.
Therefore, as shown in FIG. 4B, photosensitive resists 6c having different thicknesses can be formed.

Then, as shown in FIG. 4C, the exposed resist 6c is removed by developing, and the first resist 6e and the second resist 6f having a desired pattern are removed.
And a third resist 6g is obtained.

Further, as shown in FIG. 4D, the first resist 6e, the second resist 6f, and the third resist 6g are dry-etched while being ashed, so that the resist 6 does not exist. Part of the film 8 to be etched, a part of the film to be etched 8 below the portion where the first resist 6e and the second resist 6f are laminated, and the film to be etched 8 below the portion of only the first resist 6e
Is partially etched. After the etching, since the second resist 6f and the third resist 6g are all ashed, the first resist 6e and the second resist 6g are not ashed.
f and the third resist 6g in the portion where the third resist 6g is laminated.
Only the resist 6e remains.

Then, as shown in FIG. 4E, the first resist 6e is stripped, and the thin film 8a to be etched 8a is removed.
Then, the film to be etched 8 having a desired pattern having the film to be etched 8b having a smaller thickness is formed, and the patterning is completed.

As described above, in order to form at least two resists 6 having different thicknesses, at least two resists 6 having different sensitivities are laminated, and a photo-resist having at least two portions having different transmittances is formed. One exposure may be performed using the mask 11.

In the case of FIG. 4, if the first resist 6e has the lowest sensitivity and the third resist 6g has the highest sensitivity, the light 12c having the first transmittance can be obtained.
Is the resist 6c that has exposed only the third resist 6g, the light 12d of the second transmittance is the resist 6c that has exposed the third resist 6g and the second resist 6f, and the light 12 is the third resist 6c. The resist 6 having different film thicknesses can be formed as the resist 6c that has exposed the resist 6g, the second resist 6f, and the first resist 6e.

For example, when the thickness of the resist 6 is 400 nm,
When it is desired to make the three types of 1000 nm and 1500 nm different, the first resist 6e is 400 nm, the second resist 6f is 600 nm, and the third resist 6g is 500 n.
What is necessary is just to laminate | stack by thickness of m.

In order to form at least two resists 6 having different film thicknesses, at least two resists 6 having different sensitivities are laminated, and at least two different patterns are formed as described in the first patterning method. Exposure may be performed continuously using the photomask 11 described above.

[0055]

As described above, according to the thin film patterning method of the present invention, the resist is developed into at least two different film thicknesses, and the film to be etched is dry-etched while ashing the resist. Since a film to be etched made of at least two different materials or film thicknesses can be patterned by one etching, the number of steps involved in patterning can be significantly reduced, and the photomask may be displaced in each patterning process. Disappears.

This can be easily realized by continuously exposing the resist using a photomask having at least two different patterns and developing the resist to at least two different film thicknesses.

Further, the present invention can be easily realized by exposing the resist to light using a photomask having at least two portions having different transmittances and developing the resist to at least two different film thicknesses. .

Further, since the resist is formed by laminating at least two resists having different sensitivities, it is easy to control the resist to at least two different film thicknesses, and the resist film thickness can be accurately adjusted. Can be controlled.

[Brief description of the drawings]

FIGS. 1A to 1D are process diagrams illustrating the concept of the present invention.

FIGS. 2A to 2G are process diagrams illustrating a first patterning method according to the present invention.

3 (a) to 3 (e) are process diagrams illustrating a second patterning method according to the present invention.

4 (a) to 4 (e) are process diagrams illustrating a third patterning method according to the present invention.

FIGS. 5A to 5E are process diagrams showing a conventional thin film patterning method.

FIG. 6 is a cross-sectional view showing an inverted stagger type TFT without using an etching stopper.

FIGS. 7A to 7G are process diagrams showing a conventional thin-film active matrix substrate patterning method.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Insulating substrate 2 Gate wiring 3 Gate insulating film 4 i layer 5 n ⁺ layer 6 Resist 6a Thin portion of resist 6b Resist after etching 6c Exposed resist 6d Thinner portion of resist 6e First resist 6f Second resist 6g Third resist 7 Channel portion 8 Etched film 8a Thin film to be etched 8b Thinner film to be etched 9 Light shielding portion 10 Light transmitting portion 11 Photomask 11a First photomask 11b Second photo Mask 12 Light 12a First light 12b Second light 12c Light with first transmittance 12d Light with second transmittance 13a First semi-transmitting portion 13b Second semi-transmitting portion 51 Insulating substrate 52 Etched Film 53 resist 53a exposed resist 54 light-shielding part 55 light-transmitting part 56 photomask 57 light 58 light DOO wire 59 gate insulating film 60 i layer 61 n ⁺ layer 62 channel section 63 data lines 64 pixel electrode

Claims (4)

[Claims] A step of applying a resist on the film to be etched; a step of exposing the resist to light using a photomask having a desired pattern; a step of developing the resist into a desired pattern; Dry etching the resist, developing the resist into at least two different film thicknesses, and dry-etching the film to be etched while ashing the resist. . 2. The method of claim 1, wherein the resist is continuously exposed to light using a photomask having at least two different patterns, and the resist is developed to at least two different film thicknesses. Patterning method. 3. The method according to claim 1, wherein the resist is exposed using a photomask having at least two portions having different transmittances, and the resist is developed to at least two different film thicknesses. Method of patterning thin film. 4. The thin film patterning method according to claim 2, wherein the resist is formed by laminating at least two resists having different sensitivities.